Compound metal tube.



No. 627,992. Patent ed July ,4, I899. s. H. avensom COMPOUND METAL TUBE.

(Application filed June 14, 1897.)

{N0 Model.)

UNITED STATES 7 PATENT OFFICE.

GEORGE H. EVERSON, OF PITTSBURG, PENNSYLVANIA.

COMPOUND METAL TUBE.

SPECIFICATION forming part of Letters Patent No. 627,992, dated July 4, 1899.

Application filed June 14, 1897. Serial No. 640,706. (No model.)

To all whom itmay concern.-

Be it known that I, GEORGE H. EyERsoN, of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain This invention relates to improvements in compound metaltubes forsteam-boilers, feedwater heaters, hot-water heaters, and other apparatus of like character, and has particular reference to the provision of a compound tube, one metalof which is calculated to resist the action of'hot water and impurities in the water which otherwise would attack the other metal, and also to protect said other metal from incrustation due to the action of lime, magnesia, doc.

In water-heatin g and steam-generatin g apparatus in which single-metal iron or steel tubes are used the water-exposed surfaces of the tubes rapidly deteriorate owing to the action of the hot water and the impurities contained therein, and also when lime, magnesia, and other similar material is present in the water scale is formed and attracted to the tube-surfaces, to which it adheres, and the scale being a non-conductor of heat the efficiency of the apparatus is. impaired and greater consumption of fuel is necessary to heat the water or generate the steam, as the case may be. tered as well in the use of flue-tube boilers as with water-tube boilers; and the object of the present invention primarily is to provide a compound tube for such use, the water-exposed surface of the tube being of a metal, such as copper, which is not aifected by hot water nor by any impurities which it may contain.

A further object of the invention is to so arrange the protector metal of the compound tube that it forms a bushing for the tube-joint with the tube-sheet or boiler-head.

end View of Fig. 2.

These difficulties are encoun-- three water-tubes, showing the different steps in securing them to the head. Fig. 3 is an- Fig. 4 is a view similar to Fig. 2, with the exception that the tubes here shown are flue-tubes. Fig. 5 is an end View of Fig. 4.

Tube A, which may be of iron or steel, is provided with a lining B, of thinner metal and of such kind as will resist the action of the hot water and impurities therein, the metal I prefer to use for this purpose being copper. The inner tube or lining is made somewhat longer than tube A and adapted to fold backward on the outer surface thereof,

as shown at C. The tube being thus formed is inserted in the sheet or boiler-head D, as at the top of Fig. 2, the backwardly-turn'ed portion 0 being wider than head D, with the latter about midway its ends. An expanderof any suitable form is then applied to enlarge the compound-tube end and seal the tube-opening in the head, the tube within the head or on its inner side being enlarged to a diameter greater than the head-opening,

thereby forming an annular internal rib E on the tube. The tube end being thus expanded completely fills and seals the headopening, the backwardly-turned portion 0 of the inner tube serving as a gasket for the joint and making the joint and seal perfect.

The tube end F is then upset against the head D.

In Figs. 4 and 5 a flue-tube G is shown which is made compound by the outer copper tube H, and in this construction the protecting-tube, being on the outside, is made the same length as tube G, and the compound tube is expanded in forming the joint with the boiler-head, as described of the construction illustrated in Figs. 2 and 3.

The method of making the tubes herein referred to, and the only practical way of manu facturing them so far as I am aware, is that disclosed in the patent granted me October 7, 1890, No. 438,072.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. A water-tube boiler having its iron or steel tubes lined with impurities-resistin g material, and a protecting-covering for the end surfaces of the tubes and for their joints with the boiler-heads, whereby no portions of the iron or steel tubes are subjected to the action of water and the impurities contained therein, substantially as shown and described.

2. The combination witha boiler-head, and a water or flue tube, of a protecting-tube extending from end to end of the latter and completely covering its surface adjacent the water, the protecting-tube also extending into the opening of the boiler-head andforming a gasket for the joint, the compound tube thus formed being expanded within the head to a greater diameter than the head-opening, and the projecting end of the compound tube upset against the head,substantiall y as shown lar portion A, and inner tubular portion B r longer than portion A, the extended portion of tube B being turned back over the outer surface of tube A, for the purpose, substantially as herein shown and described.

4. The combination with a boiler formed with a tube-opening, and tube A, of protecting-tube B within tube A and of greater length than the latter, the extended portion of tube B being turned backward over the outer surface of tube A to form a sealinggasket in the tube-opening of the joint, substantially as shown and described.

In testimony whereof I affix my signature in'presenee of two witnesses.

GEORGE I-l'. EVERSON.

Witnesses:

B. M. EVERSON, ALEX. FREVV. 

